' Jim Gillespie
' Revised 8-16-2001
' Bit twiddle outputs on 74HC595 daisy chained shift registers.
' Automatically determines shift register length.
' Written to control a large number of relays.
' Uses 5 port B pins on an ATMEL 90S8515.
' NOTE: the clear_out line does not have to be used.
' The 74HC595 parts will be replaced by ALLEGRO UCN5841A parts which
' do not have a Clear_Out input pin. Software modified 1-2-00
' to use either the ALLEGRO or 74HC595 chips.
' Added M (map) function to show output status of latched bits. 2-04-00
' NOTE****: Revised 8-16-2001. DOWNTO instruction no longer supported.
' Replaced with FOR, TO, STEP -1.
' NOTE****: Compiler no longer supports this syntax:
' For I = 1 to Max_bytes + 1 where Max_bytes is a defined
' constant. Had to add a variable Limit_bytes and set it to
' Max_bytes and then add 1 to it.
' NOTE****: The 595 chips WILL NOT directly drive relays. They
' require inverting drivers. FETs, transistors or relay driver chips
' must be added. The ALLEGRO UCN5841A chips WILL directly drive relays.
' The ALLEGRO chips are recommended for this application.
' NOTE****: This software has been modified to use EITHER the 595 or
' the 5841 chips. The CLEAR input to 595 chips is no longer required.
' NOTE****: ATMEL AVR parts power up with I/O pins tri-stated.
' All pins that will be used as outputs should have 2.2k pulldown
' resistors to ground to prevent power-up glitchs.

'Additional info from Vikki Welch :

' Chip Connections (DIP is J or W package, Flat pack is D or N package):
'-----------------------------------------------------------------------
' Portb.0 to SRCLK (Dip pin 11, flat pack pin 14).
' Portb.1 to SER (Dip pin 14, flat pack pin 18).
' Portb.2 to LAST Qh' (DIP pin 9, Flat pack pin 12).
' Portb.3 to RCLK (Dip pin 12, Flat pack pin 15).
' Portb.4 to SRCLR (595 Only - DIP pin 10, Flat pack pin 13).
' !OE must be low/gnd (DIP pin 13, Flat pack pin 17).
'-----------------------------------------------------------------------

' Command set:

' Snn Set and latch bit nn. Echos command.
' Cnn Clear and latch bit nn. Echos command.
' R Reset and latch all 0's. Echos command
' T Test shift registers and sets length in bits. Returns bit length
' Does not affect 595 outputs.
' V Version. Return a string giving software version.
' I Initialize. Starts program from scratch. echos command.
' M Map. Show status of latched output bits LSB to MSB

$regfile = "8515def.dat" ' 8515 used here. Other ATMEL AVR chips possible.

$baud = 9600 ' development board uses 4 MHZ XTAL
$crystal = 4000000
'$crystal = 7372800 ' use these 2 for production version
'$baud = 9600 ' uses a 7.3728 MHZ XTAL
Const Max_in_len = 3 ' define maximum input chars
Const Max_bytes = 10 ' define max shift reg bytes possible
Const Shift_delay = 20 ' shift delay in microseconds
Const Test_pattern = &HAA ' shift reg test pattern

Dim Bytes(max_bytes) As Byte ' byte shift reg output buffer
Dim String_input As String * Max_in_len ' dim to maximum input characters
Dim Raw_echo As String * Max_in_len
Dim Read_string As String * 40 ' Gets strings read from DATA statement
Dim Value As Byte ' becomes numeric value of command
Dim Opcode As String * 1 ' one character opcode goes here
Dim Temp As String * 2 ' temp string work variable
Dim Tempbyte1 As Byte ' more temp vars
Dim Tempbyte2 As Byte
Dim I As Byte
Dim J As Byte
Dim K As Byte
Dim Max_shift_len As Byte ' Test sets this to max bits found
Dim Arry_end As Byte ' Test sets this to last array element
Dim Set_clear_flag As Bit ' flag used to set or clear a bit
Dim Limit_bytes As Byte ' For compatibility with version 1.11.6.2

' *** readability definitions ***
' NOTE: 595 pin 13 must be low/GND.
' Note: connect the Qh' of the previous 595 to the SER of the next 595.

Clock_out Alias Portb.0 ' SRCLK - 74HC595
Data_out Alias Portb.1 ' SER - of the first 74HC595
Data_in Alias Portb.2 ' Qh - of the last 74HC595
Data_in_read Alias Pinb.2 ' Qh - of the last 74HC595
Latch_out Alias Portb.3 ' RCLK
Clear_out Alias Portb.4 ' SRCLR, available on 74HC595. LOW true.

Clock_out_dir Alias Ddrb.0 ' *** define direction regs ***
Data_out_dir Alias Ddrb.1
Data_in_dir Alias Ddrb.2
Latch_out_dir Alias Ddrb.3
Clear_out_dir Alias Ddrb.4

' *** sub definitions ***
Declare Sub Clearbytes(byval Bytecnt As Byte) ' clear byte array
Declare Sub Latchbytes() ' xfer shift reg to latch outputs
Declare Sub Clearshift() ' clear shift reg
Declare Sub Test_shift_reg() ' test and determine shift reg length
Declare Sub Set_clear_bit() ' set or clear bit based on flag
Declare Sub Send_bytes() ' send byte array to shift registers
Declare Sub Map_byte() ' print binary pattern for Bytes(I)

Init: ' *** set initial conditions for I/O ***
' MAIN starts here
Set Clock_out
Reset Data_out
Reset Latch_out
Set Clear_out
' set the data direction for I/O
Set Clock_out_dir
Set Data_out_dir
Reset Data_in_dir
Set Latch_out_dir
Set Clear_out_dir

Limit_bytes = Max_bytes ' NOTE**:For compatibility with version 1.11.6.2
Incr Limit_bytes ' NOTE**:For compatibility with version 1.11.6.2

Call Clearshift() ' clear shift reg
Call Latchbytes() ' xfer zeros to outputs
Call Clearbytes(max_bytes) ' clear output byte array

Call Test_shift_reg() ' test and set shift reg length
If Max_shift_len = 0 Then
 Print "Control Board Failure !!"
Else
 Print "Control Board OK !!"
End If

Do ' ****** MAIN LOOP ******

String_input = Space(max_in_len) ' clear input string to spaces
Input String_input ' read input string
Raw_echo = String_input ' form echo string
String_input = Trim(string_input) ' trim lead and trail spaces
Opcode = Left(string_input , 1) ' extract opcode
Opcode = Ucase(opcode) ' convert to upper case
Temp = Mid(string_input , 2 , Max_in_len) ' get numeric string
Temp = Trim(temp)
Value = Val(temp) ' convert string to numeric
If Value > Max_shift_len Then ' setting or clearing beyond bit range?
Opcode = " " ' yes. set a bogus command code
End If

Select Case Opcode

Case "S" ' Set a bit
 If Value = 0 Then ' improper bit value or format
 Print "ERR 7"
 Else
 Set Set_clear_flag ' flag to set a bit
 Call Set_clear_bit() ' go set the bit in array
 Call Send_bytes() ' send to shift regs
 Call Latchbytes() ' latch the bit pattern to outputs
 Print Raw_echo ' echo command
 End If

Case "C" ' Clear a bit
 If Value = 0 Then ' improper bit value or format
 Print "ERR 8"
 Else
 Reset Set_clear_flag ' flag to clear a bit
 Call Set_clear_bit() ' clear the bit in the array
 Call Send_bytes() ' send to shift regs
 Call Latchbytes() ' latch the bit pattern to outputs
 Print Raw_echo ' echo command
 End If

Case "M" ' Print map of output bits set/reset
 If Arry_end = 0 Then ' shows LSB to MSB
 Print "ERR 7"
 Else
 For I = 1 To Arry_end
 Call Map_byte()
 Print " ";
 Next I
 Print
 End If

Case "V" ' print Version etc from DATA
 Restore Version_string ' Initialize DATA string pointer
 Do
 Read Read_string
 I = Instr(read_string , "^") ' ^ character exits loop
 If I <> 0 Then
 Exit Do
 End If
 Print Read_string;
 Loop
 Print

Case "T" ' Test interface
 Call Clearshift() ' set shift reg to all zeros
 Call Test_shift_reg()
 Call Clearshift() ' clear shift reg again
 If Max_shift_len = 0 Then ' if failure, give error message
 Print "ERR 1"
 Else
 Print Max_shift_len ' otherwise, echo shift reg length found
 End If

Case "R" ' Reset all outputs low
 Call Clearshift() ' clear shift reg
 Call Latchbytes() ' latch shift reg
 Call Clearbytes(max_bytes) ' clear byte array
 Print Raw_echo ' echo command input

Case "I" ' Initialize
 Print Raw_echo ' echo command input
 Exit Do ' re-start this program

Case Else ' unknown or improper command format
 Print "ERR 4"
End Select

Loop ' ***** MAIN LOOP END *****

Print "Control Board Reset and Initialized"
Goto Init ' I command. restart program

End

' *** subroutines ***
Sub Clearbytes(byval Bytecnt As Byte) ' clear output byte array
 For I = Bytecnt To 1 Step -1 'NOTE**: Old DOWNTO no longer works
 Bytes(i) = 0
 Next I
End Sub

Sub Latchbytes()
 Set Latch_out ' latch the shift reg to outputs
 Waitms 1
 Reset Latch_out
End Sub

Sub Clearshift() ' clear shift reg to all 0's
 Tempbyte1 = 0 ' Modified 1-2-99 for ALLEGRO chips
 For I = 1 To Limit_bytes ' send lots of zeros to shift regs to clear
 Shiftout Data_out , Clock_out , Tempbyte1 , 0 , 8 , Shift_delay
 Next I
 Reset Clear_out ' toggle the clear out line (for 74HC595 parts)
  Waitms 1
 Set Clear_out
End Sub

Sub Test_shift_reg() ' send byte pattern &HAA to
 Tempbyte1 = Test_pattern ' shift reg and count how many 8 bit shifts til
' the pattern appears in cpu input shift reg
 Shiftout Data_out , Clock_out , Tempbyte1 , 0 , 8 , Shift_delay
 For I = 1 To Limit_bytes ' NOTE**: For compatibility with 1.11.6.2
 Shiftin Data_in_read , Clock_out , Tempbyte2 , 0 , 8 , Shift_delay
 If Tempbyte2 = Test_pattern Then
 Exit For ' we got a match to pattern
 End If
 Next I
 If Tempbyte2 <> Test_pattern Then
 Max_shift_len = 0 ' no match. hardware problem!!
 Arry_end = 0
 Else
 Max_shift_len = I * 8 ' match! calc. and save number of bits found
 Arry_end = I ' last array element
 End If
End Sub

Sub Set_clear_bit() ' set or clear a bit in byte array
 K = 1
 I = Value - 1 : I = I 8 : I = I + 1 ' calc array index
 J = Value - 1 : J = J Mod 8 ' calc bit position
 Tempbyte1 = Bytes(i)
 Rotate K , Left , J ' put a 1 in proper bit position
 If Set_clear_flag = 1 Then
 Tempbyte1 = Tempbyte1 Or K ' sets the bit position
 Else
 K = Not K
 Tempbyte1 = Tempbyte1 And K ' clear bit position
 End If
 Bytes(i) = Tempbyte1 ' update array byte
 'Print Hex(tempbyte1) ' ********* debug ***********
End Sub

Sub Send_bytes()
 For I = Arry_end To 1 Step -1 ' send byte array to shift regs
 Tempbyte1 = Bytes(i)
 Shiftout Data_out , Clock_out , Tempbyte1 , 0 , 8 , Shift_delay
 Next I
End Sub

Sub Map_byte() ' show map of output latch states
 Tempbyte1 = Bytes(i) ' LSB to MSB
 For J = 1 To 8 ' 8 bits per byte to process
 K = Tempbyte1 And 1 ' test LSB
 If K <> 0 Then
 Print "1";
 Else
 Print "0";
 End If
 Shift Tempbyte1 , Right , 1
 Next J
End Sub

$data ' Put some strings in DATA for V command
Version_string: ' just for fun
Data "Jim Gillespie" , " 08-16-2001" , " Version 5.01"
Data " Serial #" , "000401" , "^"